Taxonomic Characterization: One-eyed. Placement of the spiniform seta of leg 5 is medially rather that subterminally on the distal (exopodite) segment. There is lateral extension and rotation of the lateral spine of leg 2 exopodite segment 1. Lack of spines on pediger 5 (Fiers et al., 1996).

Evolutionary Origins: Along with M. yutsil and Keiferiella delamarei (Lescher-Moutoué, 1971; 1976) (known from the saturated zone of a karst system in France), this species is considered a species-flock which has radiated as a specialist within a highly dynamic geomorphological environment. It is as if M. yutsil shared a cervicular living ancestor with M. chaci, but evolved for a planktonic existence in the Yucatan cenotes. It has been suggested several times that ancestral copepods were epibenthic, giving rise to planktonic forms (Fiers et al., 1996).

Conservation Status: Restricted to one well and one cenote of the Yucatan Peninsula.